Origin

The word monkey first entered English in the 1500's, deriving from the Arabic word maimun. Although the term strictly refers to lower primates, and not the higher apes, it is generally used to refer to all primates except humans and gorillas.

Monkeys, due to their playful antics and mimicry, have long been a source of amusement and a chief attraction at zoos. 3 However, the precise origin of barrel of monkeys, first recorded in the late 1800's, is unknown. We can speculate that it is an allusion to releasing a barrel of monkeys, and the funny antics that would ensue. 1

The related expression barrel of laughs did not originate until the late 1900's, and appears to be a variation of barrel of monkeys.

The idiom inspired the popular children's toy/game Barrel of Monkeys, developed in 1966 by Lakeside Industries of Minneapolis, Minnesota, and later marketed by Hasbro. The game consisted of twelve plastic monkeys in a plastic barrel. The monkeys could be different colors: yellow, blue, red, and green; or all one color. The barrel was red, yellow, or blue. The object of the game was to see how many monkeys you could pull out of a pile at once, by hooking together their arms. 4